Whatnot shelf



FIG. 1 is a top perspective view of a whatnot shelf showing my new design;

FIG. 2 is a top plan view;

FIG. 3 is a front elevational view;

FIG. 4 is a bottom plan view; and

FIG. 5 is a right side view;

FIG. 6 is a left side view; and,

FIG. 7 is a rear elevational view. 

The ornamental design for a whatnot shelf, as shown and described. 